Method of making three dimensional display panel



Jan. 16, 1968 R. M. SLIPP 3,

METHOD OF MAKING THREE DIMENSIONAL DISPLAY PANEL Filed Aug. 20, 1964PHOTOGRAPH DEVELOP PHOTO ENGRAVE CAST STRIP FIGB F l G. 6

F G 7 44 F G. 5 INVENTOR. ROY M. SLIPP r\\\\\\\\t BY F l G 8 46WMUIQW'AOI-OQEV ATTORNEYS United States Patent Office Patented Jan. 16,1968 3,364,090 METHOD OF MAKING THREE DIMENSIONAL DISPLAY PANEL Roy M.Slipp, Seekonk, Mass., assignor to Clearfloat, Inc., Attleboro, Mass., acorporation of Massachusetts Filed Aug. 20, 1964, Ser. No. 390,962 2Claims. (Cl. 156-245) ABSTRACT OF THE DISCLOSURE A transparent castingis formed with one surface being smooth and the opposite surface castwith a relieved halftone image. When the casting is illuminatededgewise, the image presents a very striking appearance which is quitelife-like and has a three-dimensional effect.

The image is obtained by casting a transparent plastic over a half-tonephoto-engraved plate of the image, allowing the plastic to cure, thenseparating the plate and castmg.

This invention relates generally to display products and theirmanufacture, and more particularly is directed towards a transparentpanel having a half-tone relief image thereon providing unique opticaleffects particularly when illuminated along an edge. This invention alsois directed towards a novel process for manufacturing transparentdisplay products having half-tone relief images thereon.

There have been available heretofore for use in advertising displays andthe like transparent panels of which one surface is embossed or etchedin a particular pattern. These display panels heretofore have beenfabricated by hand engraving, imprinted or molded on hand shaped dies.Panels produced in this fashion, by reason of the high degree of skilland art work involved, have been quite expensive and able to depict buta relatively restricted type of scene. As a result, panels of this sorthave not found wide acceptance in the trade but rather have been usedonly as novelty items. Furthermore, panels of this type heretofore havebeen somewhat lacking in detail, luminosity and three dimensionaleffect.

Accordingly, it is an object of the present invention to provideimprovements in transparent display products having a relief imagethereon.

Another object of this invention is to provide a transparent displaypanel having a relief image thereon and characterized by improvedilluminating qualities, detail and life-like representation.

Still another object of this invention is to provide an improved processfor producing transparent products such as panel displays and the likewith relieved half-tone images thereon.

More particularly, this invention features a transparent display panelhaving one side configured in half tones to produce a relief imagethereon visible on both sides of the panel. Relief may be defined as afigure or design formed by elevations and depressions. The relievedsurface is formed by casting a transparent stratum over a photoengravedplate or replica thereof and permitting the stratum to harden into asolidified panel. The solidified transparent stratum or panel is thenseparated from the plate and the surface of the panel which has beenoverlying the face of the plate will be formed with a permanenthalf-tone relieved image corresponding to the plate image. The resultingpanel, when illuminated along an edge thereof, displays a particularlybright image characterized by depth, detail and remarkable life-likequalities.

However, these and other features of the invention, along with furtherobjects and advantages thereof, will become more fully apparent from thefollowing detailed description of preferred embodiments of theinvention,

with reference being made to the accompanying drawings, in which FIG. 1is a flow diagram showing the process for making transparent panelsaccording to the invention,

FIG. 2 is a view in perspective of a transparent display panel madeaccording to the invention,

FIG. 3 is a greatly enlarged detail of the FIG. 2 panel showing thehalf-tone clot formation,

FIG. 4 is a sectional view in side elevation of the FIG. 2 panel also ona greatly enlarged scale,

FIG. 4A is a view similar to FIG. 4 showing a modification of theinvention,

FIG. 5 is a view in perspective showing the casting step in the processof producing the FIG. 2 panel, and

FIGS. 6, 7 and 8 are sectional views in side elevation somewhatschematic showing a modified process for producing the FIG. 2 panel.

Referring now to the drawings and to FIGS. 2, 3 and 4 in particular, thereference character 10 generally indicates a transparent panel of arigid transparent plastic material such as acrylic or the like. Thepanel 10, as best shown in FIG. 4, is formed with front and rear faces12 and 14, respectively, with the front face being smooth and fiat whilethe rear face is cast with a grid pattern defining a plurality of smallshallow pits 16. These pits vary in size and depth throughout the rearface 14 with the shallow pits producing a dark effect when side lighted,as by a lamp base 17, while the deeper pits produce a light effect. Inany event, the pits correspond to half tones and according to their sizeand depth, define a relief image 18 visible on both sides of the panel.This effect is due to light refracting and reflecting from the number ofsmall pits dispersed over the rear surface of the panel.

As best seen in FIG. 3, the pits 16 are generally circular and appear asindividual three dimensional dots, which in some cases blend withadjacent dots to represent white or high light portions as at 20 orappear as mere pinpoints to indicate very dark portions as at 22. Theremaining circular dots or pits 16 which are more clearly defined,correspond to various shades of grey depending upon size and depth.

The optimum relief effect is best achieved with a relatively coarsehalf-tone screen. In practice, a screen of 50 lines per inch or coarsershould be employed for the proper effect and a 37 screen has been foundto produce an ideal half-tone relief effect. This half-tone reliefeffect is enhanced by a coarse texture in which the pits have an averagedepth of .008 inch or deeper to achieve the desired light refraction andreflection.

Referring now more particularly to FIG. 4A of the drawing there isillustrated a modification of the invention and in this embodiment atransparent panel 24 of a material such as used in the panel 10, acrylicplastic for example, is formed with a fiat smooth front surface 26 andan embossed or cameo rear surface 28. The rear surface will be seen tobe cast with a plurality of small dot-like protrusions 30 generallyconvex and of various sizes. These protrusions correspond in reverse tothe pits 16 of the FIG. 4 embodiment and produce an analogous efiect.The protrusions are arranged in the same grid pattern and the size andextent of each protrusion vary according to various shades between lightand black to produce the desired half-tone relief effect on the rearface of the panel.

The transparent half-tone relief panels may be pro duced by theprocesses described below. A desired subject or scene is photographedand developed in the usual fashion and a half-tone photoengraved plate32 is made from the photograph. In making the plate 32 a screen of theproper texture, preferably having 50 lines to the inch or coarser, isemployed in order to achieve the desired effect. The half-tone platesare made from photographs, Wash drawings or other art work done incontinuous tones that range from white through intermediate greys toblack, as distinguished from all black lines and areas of line copy. Toreproduce or simulate these tones use is made of the half-tone screenwhich in its standard form consists of two plates of glass each ruled oretched with fine parallel lines and cemented together face to face withthe lines on one crossing the lines of the other at right angles. Thelines are opaque, the spaces between them transparent and the lines andspaces are the same width.

In making the half tone the screen is placed in the camera directly infront of the film or photographic plate but not in contact with it. Thespace between the screen and the photograph varies with the nature ofthe copy but is generally /8 to /2 inch. The photograph which has beenmade through the screen consists of an image made up of dots ofdifferent sizes. In white areas such as highlights, these dots willoverlap producing on the negative the effect of very fine white dots ona black background. Similarly, areas of black on the copy register onthe negative as pinpoint black dots and the greys register as dots ofvarying intermediate sizes.

The half-tone negative is then etched onto a heavy plate such as 11gauge brass for example. The resulting half-tone plate consists ofthousands of tiny dots of different sizes and depths corresponding tothe shading on the original photograph. When the original photograph isa positive, the dark areas are etched into the plate deeper than thelight areas to form a female or negative plate. A male or positive platemay be made by using a negative print as copy or using a photographicpositive instead of a negative in etching the plate. In using a maleplate the FIG. 4 intaglio panel will be produced, whereas a female platewill produce the cameo-like panel of FIG. 4A.

For purposes of this description relief is intended to include both theintaglio surface of FIG. 4 and the cameo-like surface of FIG. 4A. Also,unless otherwise specified, photoengraved plate is intended to includeboth male and female plates.

The plate 32 whether it is male or female is laid face up on ahorizontal surface and a dam 34 is placed around the edges of the plate.A suitable transparent plastic 36 in liquid or semi-liquid form is thenpoured over the face of the plate 32, completely covering it, and theplastic is allowed to cure into a solid casting. Once the casting haspolymerized, it is separated from the plate and, if the front surface ortop of the casting is not sufficiently smooth, it is ground flat andpolished to produce the panel 10. It will be understood that the rearface of the panel will have taken on the image on the place, this imagebeing relieved either in the form of half-tone intaglio pits as in FIG.4, or half-tone cameolike protuberances as in FIG. 4A, depending uponwhich type of plate is employed.

In the practice of this invention, various types of transparent plasticsmay be employed to advantage. One such plastic which has been found tohave given excellent results is transparent acrylic resin such as aslurry mix of methyl methacrylate. This slurry gels quickly, has a Wshrinkage factor and quickly takes shape. This slurry may consist of 60%hardened polymers and 40% nonhardened monomers. Other material such astransparent epoxies and polyesters may also be used.

Referring now to FIGS. 6, 7 and 8, there is illustrated a modifiedprocess of producing a panel such as shown in FIG. 4 or 4A. Thisprocess, which may be referred to as skin casting, includes the steps ofpouring a thin skin 38 of suitable transparent plastic in a liquid formover the photoengraved face of the plate 32. The skin casting may be anacrylic resin, both in liquid or semiliquid form, for example. While theskin casting 38 is still in liquid form, a fiat rigid stratum 40 oftransparent plastic material such as acrylic, for example, is presseddown onto the skin casting 38, as suggested in FIG. 7. The skin casting38 and stratum 40 should be of compatible materials so that the twostrata will coalesce without an interface boundary. In any event, oncethe skin casting 38 has polymerized, both the skin casting andnow-joined stratum 40 are stripped from the photoengraved plate 32. Ifdesired they may be placed in an autoclave for faster polymerization.

With this process, there is no need to grind the front surface of thefinished panel since the stratum 40 is provided in =flat form so thatthe finished panel is ready for use as soon as the skin casting haspolymerized against the stratum 40 into the single integrated panel 42('FIG. 8) having a flat smooth front surface 44 and a ha'lf-tonerelieved rear surface 46.

It will be understood that the stratum 40 may be of any transparentplastic material which is compatible with the skin material and servesas a medium to transmit light to the skin casting and to support therelatively thin skin. It also will be understood that the photoengravedplate 32 may be of any suitable material such as brass or steel or areplica thereof such as electrotype, for example.

The panel may be made in various sizes and shapes depending upon theiruse. The process lends itself to the production of very large sizedecorative panels for use as room dividers, doors or large advertisingdisplays. The optimum relief effect is achieved by edge lighting thepanel and using a relatively coarse half-tone screen when reproducingthe selected image. Any scene or subject matter which can bephotographed may be faithfully reproduced on the panel with theprocesses described above.

The panel may be made up with a wide variety of scenes, permanently castthereon, providing particularly attractive products useful in a numberof different applications such as the building trades, advertising andthe like.

While the invention has been described with particular reference to theillustrated embodiments, it will be understood that numerousmodifications thereto will appear to those skilled in the art. Forexample, the casting may be done with a number of different materialsunder different conditions of temperature and pressure to achieve thedesired casting.

Accordingly, the above description and the accompanying drawings shouldbe taken as illustrative of the invention and not in 'a limiting sense.

Having thus described the invention, what I claim and desire to obtainby Letters Patent of the United States is:

1. A process for producing a transparent display panel having ahalf-tone relief image cast on the face thereof, comprising the steps of(a) forming a photoengraved half-tone plate of said image,

(b) casting over said plate a relatively thin stratum of transparentplastic in liquid form,

(c) applying a relatively thick rigid stratum of transparent materialover said thin stratum,

(d) allowing said stratum to solidify so that the face of said thinstratum overlying said plate will be bonded to and formed with apermanent half-tone relief image, and (e) separating both of said strataand said plate. 2. The process of claim 1 including the step of heatingboth of said strata to polymerize said thin stratum.

References Cited UNITED STATES PATENTS 2,180,002 11/1939 Ford 1612 OTHERREFERENCES Advances in Xerography, 19584962. Photographic Science andEngineering, vol. 1, No. 1, January-February 1963, pp. 12, 13, 18 and19.

JACOB H. STEINBERG, Primary Examiner.

